This invention relates generally to fluid flow control valves and more particularly to poppet valves for use on a sootblower device and having means for externally adjusting the flow restriction through the valve.
Sootblowers are typically used with large scale boilers for discharging a cleaning medium which provides a thermal and mechanical shock to dislodge combustion and flue gas deposits forming on the heat transfer surface of the boiler. In this manner the efficiency of the boiler can be maintained.
Generally, poppet valves are utilized with sootblowers to control the discharge of a cleaning medium, such as air, water or steam, from a source into a lance element which directs the cleaning medium toward the surfaces to be cleaned.
A widely used flow control valve used in sootblower applications is a poppet type valve having an internal flow restriction control disc. In one popular valve of this type, the restriction control disc is threaded onto the valve stem guide. To adjust the flow restriction of the valve, a access plug is removed from the body of the valve. The restriction control disc is peripherally notched so that when the plug is removed, the disc may be turned by pushing or prying with a small bar or screwdriver so as to rotate it along the threads of the valve stem guide. As the restriction control disc moves along the threads, the effective flow area between the restriction control disc and the valve seat is varied. A poppet valve of this particular type is illustrated in U.S. Pat. No. 3,164,364 which is commonly assigned to the Assignee of the present application.
The space which houses the restriction control disc in the above mentioned type of poppet valve is limited. Also, a substantial period of time is required to remove the access plug, adjust the restriction control disc, and replace the access plug. Thus any adjustment of the valve restriction will result in a significant sootblower down time.
A more convenient restriction adjustment mechanism for a poppet valve, both in terms of ease of operation and accessibility, is disclosed in U.K. Patent No. 1,565,768, which is also commonly assigned to the Assignee of the present application.
In the U.K. patent, a poppet valve is provided with a internal restriction control disc which is threaded onto the stem guide for movement toward and away from a secondary valve seat. The restriction control disc is provided with a toothed periphery which meshes with a worm gear journaled within the body of the valve. The worm gear is externally driven and when the worm gear is rotated, the restriction control valve is also rotated and moves toward or away from the valve seat, thereby adjusting the effective flow area of the valve.
The present invention represents and advancement of fluid flow control valves having an externally adjustable restriction feature. A primary object of this invention is to provide improved regulation of the flow restriction, while also improving the actuation mechanism so as to provide for a more convenient restriction adjustment.
A poppet valve embodying the principles of the present invention includes a valving mechanism which is typical of those used in the industry in that it includes a valve head which is movable from a closed position in contact with a valve seat and an open position in which the valve head is spaced from the valve seat. The valve head is actuated by a valve stem extending through the body. Normally, the valve system is biased by a spring so as to hold the valve head in its closed position. A pivotable trigger operates on the valve stem so as to compress the spring member, axially move the valve stem and displace the valve head from the valve seat thereby opening the poppet valve.
The externally adjustable restriction control assembly of the present invention cooperates with the valve stem and another seat which encircles the inlet port and faces interiorly of the chamber. A threaded stem guide is fixed to the valve body and extends into the chamber toward the seat. A portion of the valve stem, interior of the chamber, includes a driver surface around which is mounted a restriction control disc. The restriction control disc is engaged with the driver portion such that it is rotationally fixed therewith but axially movable relative thereto. The restriction control disc is also threadably engaged with the screw portion. That portion of the valve stem which is external of the valve body includes a portion which can be utilized to rotate the valve stem.
By rotating the valve stem, the restriction control disc is rotated and moved axially along the threaded engagement of the screw portion toward or away from the seat thereby effectively altering the flow gap between the seat and the restriction control disc.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawing.